Lesson 1.1
Lineweights: The Grammar of Hierarchy
The single skill that separates a drawing that reads instantly from one that's a flat, confusing mess. Not what you draw — how heavily you draw it.
Start hereShow two students the same floor plan. One drew every line the same thickness. The other varied the weight. The second plan looks three-dimensional, reads in a glance, and feels professional.
They drew the identical geometry. The only difference is which lines were told to shout and which to whisper.
01 — The core idea
Heavy means “I'm important”
In 0.1 you learned a drawing is an argument. Lineweight is how the drawing decides what to say loudest. A thick line and a thin line carry the same shape but a different volume — and your eye reads volume as importance before it reads anything else.
There's a strict order, and it's the same in every country. The line where you cut through solid material is heaviest. Edges you can see but didn't cut are medium. Lines that are hidden, or just references (dimensions, grids) are lightest. Get this hierarchy right and a plan organises itself for the reader automatically.
Drag the walls down to match everything else. Watch the plan go flat and dead.
02 — The three tiers
Cut, seen, reference — and the pencils for each
The hierarchy is three tiers. Here's each one, what it's for, and — because we draw with both hands — the pencil grade and the digital pen weight that produce it.
Notice the ratio matters more than the exact numbers. As long as cut is clearly heavier than seen, and seen clearly heavier than reference, the reader's eye sorts the drawing instantly. A rule of thumb: each tier is roughly twice the weight of the one below it.
| Tier | What it's for | By hand | On screen |
|---|---|---|---|
| 1 · Cut | Walls, columns, anything sliced through | 2B pencil | 0.50–0.70 mm |
| 2 · Seen | Door swings, furniture, edges you see | HB pencil | 0.25–0.35 mm |
| 3 · Reference | Dimensions, grids, hatching, hidden lines | 2H pencil | 0.13–0.18 mm |
03 — The most common mistake
The flat drawing
Almost every beginner makes one mistake: drawing everything at one weight, usually because it's faster or the pen never changed. The result is a “flat” drawing — technically correct, but exhausting to read, because the reader's eye has to do all the sorting the lineweights should have done.
The fix is a habit, not a talent: before you draw a line, ask which tier is this? Cut, seen, or reference. Three choices. Make it every single time and your drawings gain depth for free.
Pen weights follow the ISO 128 line-width series (0.13, 0.18, 0.25, 0.35, 0.50, 0.70, 1.0 mm) — each step roughly √2 larger, so they stay distinct when a drawing is photocopied or scaled down. This series is used worldwide, which is why a set of CAD pens labelled in millimetres works the same in Bengaluru or Boston. Hand-drawing grades (2H/HB/2B) are the looser, analogue cousins of the same idea. Same grammar, two tools.
15 minutes, both hands
- By hand, trace a simple floor plan twice — once with a single pencil, once switching between 2H, HB and 2B for the three tiers.
- Hold both at arm's length. Which one reads faster? Note what your eye lands on first in each.
- In any CAD tool, draw a rectangle room and assign three pen weights to walls / door swing / dimension line. Plot or export and compare to your hand version.
- Write the three tiers from memory: cut → ___, seen → ___, reference → ___.
Key terms — added to the Drawing Atlas
- Lineweight
- The thickness of a drawn line. Used to show importance — the eye reads heavier lines as more important.
- Lineweight hierarchy
- The three-tier ordering of line thickness: cut (heaviest), seen (medium), reference (lightest). The same everywhere.
- Cut line
- The heaviest line, marking where solid material is sliced through — walls, columns. Tier 1.
- Seen line
- A medium-weight line for visible edges that weren't cut — door leaves, furniture, fixtures. Tier 2.
- Reference line
- The lightest line, for dimensions, grids, hatching and hidden elements. Tier 3.
- Flat drawing
- A drawing where every line is the same weight, so nothing leads the eye. The most common beginner mistake.
- ISO 128
- The international standard for technical drawing lines, including the line-width series (0.13–1.0 mm) used worldwide.
Check yourself
3 quick questions — pick an answer to see why.
Q1In a floor plan, which lines should be drawn HEAVIEST?
Q2The three lineweight tiers, heaviest to lightest, are:
Q3A “flat drawing” is one where…
- Lineweight is how a drawing decides what to say loudest — the eye reads weight as importance.
- Three tiers, same everywhere: cut (heaviest) → seen (medium) → reference (lightest).
- Ratio beats exact numbers — each tier roughly twice the one below.
- The flat drawing (all one weight) is the most common beginner mistake; the fix is asking “which tier?” every line.
Weight tells you how loud a line is. But how does a line say what kind of thing it is — solid, hidden, or a centre?